Apparatus for alternating the polarity of current in electric circuits.



I e. BABOOOK. APPARATUS FOR ALTERNA'IING THE POLARITY 0F GUBREN'I' IN ELECTRIC CIRCUITS.

APPLICATION FILED JUIB 14. 190B.

Patented Feb. 1, 1910.

In yew (or Z Altar/7g UNITED STATES PATENT OFFICE.

GAR-RISON BABCOCK, OF ROCHESTER, NEW YORK, ASSIGNOR TO TELEGHRONOMETER COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

APPARATUS FOR ALTERNATING THE POLARI'IY OF CURRENT IN ELECTRIC CIRCUITS.

Specification of Letters Patent.

Patented Feb. 1, 1910.

Application filed June 14, 1909. Serial No. 502,090.

To all whom it may concern: i

Be it known that I, GARRISON BABGOGK, of Rochester, in the'county of Monroe and State of New :York, have invented certain new and useful Improvements in Apparatus for Alternating the Polarity of Current in Electric Circuits; and 'I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to 'the"accompany1ng"drawings, forming apart of this specification,-and to the reference characters marked thereon; Myrpresent invention has'ifor its object to provide an electrical apparatus for supplying to a line circuit a direct current which periodically flows in opposite directions for t-he'purpose ofoperating such devices as may-be adapted to be actuated by a change in'the polarity or direction of flow of the current in the operating circuit in which they are arranged.

A specific'purpose tori-which my present invention is' adapted is that" ofiisupply ing direct current to the lilies oi telephone exchanges which-is adapted to beusied for talking purposes andf also actuating service metering devices which may be so constructed as to be capable of operation, during the use of the subscribers line, by a mere reversal in the directionof flow or change 0 polarity of the current. I

To these and "other ends the invention consists in certain improvements and combinations of parts all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

The figure of drawing illustrates diagrammatically one form of apparatus which may be employed for carrying out my invention.

In the illustration I have shown in conjunction with my apparatus a telephone system comprising a central office apparatus and two subscribers lines, which although they form no part of the present invention, are illustrated to give a clear understanding of the operation and function of the present form of apparatus which I have devised for operating them.

The present apparatus may be employed for supplying current of opposite polarity periodically to a circuit for any purpose for which it may be used but as its more important service is to be found in connection with telephone systems equipped with service metering devices, a type of which is shown in United States Letters Patent No. 912,268, granted February 9, 21909, to CharlesM. Beattie, the metering mechanism shown therein has been employed as an example of one form of mechanism for the operation of which my apparatus is well adapted.

In the operation of a metering device arranged on a telephone circuit which is ac tuated by variations or changes in the direction of the flow of the current on the line,

.it is desirable that the changes in the current from positive to negative. and vice versabe graduated both as the current in one direction diminishes and as it increases in the other direction; In other words, it is essential that the potential change of the current :'.be perfectly regular so that no vibration due to this cause will be imparted to the diaphragm of the receiver of the telephone and no inconvenience will be'egperie'nced by the subscriber by rea'sonE of the change in the direction of the flow of current occurring during the use of his instrument. v v

In order to carry out the object as above outlined briefly, I employ two generators of the direct current type which are connected in series in opposite polarity between the two sides of the line circuit their fields being arranged to be alternately excited. The armatures of both generators are in constantrotation and the coils of each alternately operate as a conductor for the current of the other when the field coils of the latter are excited. Associated with these generators are electrolytic devices which are bridged to the terminals of the generators and are employed as a means for absorbing the slight variations of the polarity of the current produced during the operation of the generators due to commutation changes of the current which may be noticeable during the operation of either of the generators. Various forms of devices of this character may be employed but the one I prefer to use, especially when the apparatus is employed in connection with a telephone system, is a storage battery as I propose to use it as a source of current for the operation of part of the central oflice telephone apparatus and to so associate it with the generators that the battery may be maintained charged to its full capacity by the generators.

.0 positive In the drawings I have shown two direct current generators A and M each having the brushes a m and a m indicated respectively as positive and negative. These 5 brushes are arranged in the line circuit intremities 3 terminatev in. icontactsa, m with which cooperatesa switchJarnr-ga Tlie'current. employed fori rexcitin'g the generators is obtained from a dynamo indicated by G having the brushes gfhithe former being connected with the conductor f, by the tap-g while the latten is united toithe switch arm g byithe wire'gln Hui? at: n.

Anyi suitablmmeansimayibei employed for 1 actuatin thegswitch armeigr buti as it is -preferab eatb movenitl periodically at given graduations nofirhime; i1 rqimeifen M01 operate it by anwelectro-maghetiH :anranged time: circuit which is opened andvclosedi by icontacts actuated by a clock trazinll' In theipresent 30. instance the? circuitmfthe unagnet islshown provided-3* with a decal) batteryiand with a pair of contacts h,- h",'the1latter beingzada'pt- 1 ed to be'srn'ovedto a position menswear-cir- .cuit:by a ea'nr h" drivenibyitheiclock train h and=so arranged that theuniigneb willifbc err ergized to attract the switch arm 'mand be denergized to permit it to retnrn to its normal position undenthe influence of the spring g, at given intervals of time which 40 may beexpressed in seconds.

The armatures of the generators A and M it will be understood 'are driven continuously'by any suitable form of motor as is also the armature ofthe dynamo G, or the armature of-the excitingmachine which it will be understood may be employed in place of the dynamo in the event the exciting current is taken from 'feed wires. For the sake of clearness, these elements have been separatedin the illustration but in practice they may be combined as separate parts of a single machine the several armatures being mounted on a single driving shaft;

- In order to eliminate line' disturbances and to remove from the telephone line noises caused by the slight fluctuations of the current due to the action of commutation, which may be distinguished in a telephone receiver by a humming sound and also to insure a gradual decrease of the potential in one direction and its equal gradual increase in the other direction, I associate with the generators electrolytic devices preferably a storage battery which is divided into two parts as indicated by-B andX which are connected -the aluminum cell X.

minumcells are mentioned specifically, it will be understood that in some instances other devices may be employed with equal .yeflect for preventing outflow of current from the batteries.

across the terminals of both generators each battery section being so disposed as to coir stitute a charging load upon one of the generators when in operation. \Vhen storage batteries are employed the electrolytic dc vices also include aluminum cells B and X containing an electrolyte. said cells being disposed in the circuits of the batteries be tween the latter and the generators in such position as to prevent their discharging current into the generators, or to short circuit. each other, yet permitting them to receive the current from their respective generators. These parts are shown in the illustration as arran ed in the following manner: Section B of t e electrolytic device is arranged with its negative pole connected by the wire I) to the bus bar C, its positive pole being similarly connected to the bus bar D by the wires tb yb between which is located the aluminum icell B.

The other section or battery X is similarly connected with the bus bar I) by the conductor an and with the bus bar C by conductors w, 0: between which is arranged Although the alu- In operation the exciting current being ;-applied to the coil (1. of generator A, when the switcharm g is engaged with contact a said generator produces current of one polarity which is transmitted over the following line circuit: bus bar C, conductor 0, brushes (1 a, conductor 0, brushes in m wire (5, bus bar D. thence over the line circuit returir ing to bus bar C. When the switch arm r isattracted in engagement with contact m the source of exciting current is then trans ferred to the coil in? of generator M which latter commences to pick up the load and Supplies to the aforedcscribed circuit the full potential current of the opposite sign. It 1 will be noticed that the building up of the voltage by the generator M occurs while the coil of generator A is deenergizing. or 10s ing its saturation. and there is therefore in fact a practical balance between the two generators. From an observation of the illustration. it will also be seen that during the operation of generator A that when the internal resistance of the electrolytic devices. or battery B. is reached by the voltage on the line that current will traverse the following path: brush (a conductor 6, brushes m, m, conductors (1. cell B. wire Z). battery B, wires 1). (r, and brush a, said circuit being completed through the cell B. when the required voltage of the imposed load is reached. Similarly current will be transmitted from the generator M to the battery X when the voltage transmitted to the line by it reaches the given amount as it will then overcome the resistance in the following circuit: brush m, conductor a, brushes a, a, wires 0 02 cell X, wire 00, battery X, conductors w, d and brush on.

The telephone system illustrated diagrammatically shows two subscribers telephone instrument circuits, indicated generally by I and J, each of which comprises the usual transmitters T and receivers R, arranged in circuits comprising the line wires 2', 7', respectively. The usual switch board jacks at the central office comprise the tip and sleeve contact springs with which cooperate the plugs of the answering and calling cord circuits, indicated in the present instance by Z, l and is, k terminatin in the tip and sleeve contacts as shown. he metering device for recording the length of time the instrument circuit of the callin subscriber is in use is located at the subscri ers station and is indicated as a series of dials n. These are operated by electromagnetic devices associated with the instrument circuit and adapted to be actuated by current thereon at iven intervals of time by theaf oredescri ed devices located atthe centralofiice which as before described are so arranged as not to interrupt the undulatory voice currents which may be traversing the line and to prevent a disagreeable click or vibration in the diaphragm of the subscribers closed circuit This apparatusis arranged to gradually decrease thepotential 01E saidrcurrent scribed, comprising two generators arranged to supply current of opposite polarity to a and to subsequently increase; it gradually to the maximum! voltage. i

The conductors of the answering cord are connected with opposite sides of the battery B from which current for talking purposes is supplied to the callin subscribers line, the connections being ma c with this battery in the manner shown so that current flowing in but one direction is obtained and the meter of the calling partys line will not be actuated. However, should it be desired in special instances to cause the called partys register to be actuated, the conductor Z may be attached to the bus bar D as indicated by the dotted line Z in place of the connection, now shown, leading directly to one side of the battery.

The equalization of the current consumption of the batteries B and X may be effected by employing the latter as a source of current for operating the line signals or the supervising mechanism of the switch board. In practice however, it is customary to employ the two batteries for supplying current to an equal number of sets of calling cords as will be understood.

I claim as my invention.

1. An apparatus of the character described, comprising two generators arranged in series and connected so as to be of opposite polarity and havin fields, means for alternately exciting sai fields, and means assoarrange ciated with the generators for absorbin the varying current of each polarity pro uced during the operation of one or the other of said generators.

2. An apparatus of the character described, comprising two direct current generators arranged in series but polarly opposed and having fields, means for alternately exciting said fields and an electrolytic device in circuit with said generators and adapted to absorb the variations of the current produced during the operation of the generators.

3. An apparatus of the character de scribed comprising two current generators connected in series but arranged 1n opposition to each other, means for alternately exciting said enerators to produce current of opposite p0 arity and means associated with said generators for absorbing the variations of current so produced due to commutation changes occurring therein.

. 4. In an apparatus of the character described, comprising a line circuit for electrical operating urposes, two generators to supp y current of op osite polarity to said circuit, means for a ternately exciting them and electrolytic means connected across the terminals of both enerators for preventing transmission to t e line circuit polar and commutator variations of the generated current.

5.111 an apparatus of the character deline/circuit, means for alternately exciting said generators, separate batteries connected across the terminals of each generator and means interposed in the battery circuits for preventing the flow of current therefrom to 0 the line but adapted to permit current to How from the generators to said batteries.

6. An apparatus of the character described, comprising two direct current generators each comprising the usual armature and field llO windings, commutators and brushes, :1 line circuit for electrical operating purposes leading through the brushes and so connecting them in series that the enerators when operated will supply said line circuit with current of opposite polarity, a source of current for exciting the generators and switching devices for alternately connecting said source with the fields of the res ective generators and devices associated with the generators for imposing a sufiicicnt electrical load on each of them to effect a gradual reduction of the current of one polarity on the line circuit produced by one generator, and

and olarly opposed between the two sides of a ine circuit for electrical operating purposes, for the purpose of supplying said line at different times with current of opposite polarity, the arniaturcs of said generators bein rotated continuously, means for alternate y exciting said generators, batteries connected across the terminals of said gen erators and electrolytic cells interposed in said connections between each battery and its respective enerator.

8. The com ination with a plurality of subscribers telephone instrument circuits, and a central otfice equipment comprising answering and calling cord circuits for interconnectin said circuits, of two current generators o opposite polarity arranged in series and connected to the answering cord circuits and adapted to alternately sn )ply calling subscribers lines with current 0 opposite polarity, batteries associated with the generators and cord circuits and arranged to supply current for the called subscribers lines and for absorbing variations of the generated current produced during the 0 eration of the generators and means for a ternately exciting the latter.

9. An apparatus of the character described, com rising two direct current generating macl iines each comprising the usual commutators, brushes, and armature and field windings, said generators being arranged to produce current of opposite polarity, a line circuit for electrical operating purposes leading through said brushes, a source of current for exciting the fields of the generators, switching devices for disconnecting said source with the field of one generator and connecting it with the field of the other generator, and electrolytic devices arranged in circuit with the generators for absorbing variations of the current produced during the operation of the generators,

l r l l l 10. An apparatus of the character de scribed. comprising two direct current gencn ating machines each con'iprising the usual commutator-s, brushes. and armature and field windings, a line circuit leading through the brushes. said circuit and generators be ing disposed so as to produce current of opposite polarity in the circuit at alternate intervals of time, a source of current for exciting the generators tern'iinating in a switch arm, terminals of the field windings oi the generators forming contacts with which said arm alternately cooperates, devices for periodically shifting the arm from one contact; to the othe' and separate means associated with each generator for absorbing variations of the generated current due to rounnutation changes.

11. The combination with a plurality of subscribers telephone instrument circuits and a central oflicc eqniJment con'iprising answering and calling cord circuits and serv ice supervising mechanism, of two current generators of opposite polarity connected in series and arranged to supply continuous current of opposite polarity to the answering cord circuit, means for alternately and periodically exciting said gene 'ators, batteries in circuit with the generators, calling cord circuits, and supervising mechanism, devices interposed in the battery circuits between the latter and the generators for preventing the flow of current from the batteries but permitting it to flow to them from the gcner ators and devices arranged in the instrument circuits adapted to be actuated by the reversal in the direction of flow of current thereover.

GARRISON BABCOCK.

\Vitnesses RUSSELL B. GRIFFITH, G. \VILLAIm RICH. 

